Comparison of Marginal Bone Loss in Simultaneous Versus Delayed Implant Placement Following Horizontal Ridge Augmentation with Autogenous Lateral Ramus Bone Block

Statement of the Problem: Alveolar ridge resorption after tooth extraction may interfere with optimal dental implant placement. Purpose: This study aimed to compare the marginal bone loss (MBL) and thickness of the buccal aspect of the augmented site in simultaneous versus delayed implant placement following lateral ramus horizontal ridge augmentation in the posterior mandible. Materials and Method: This prospective cohort study was conducted on patients who required horizontal bone augmentation of the posterior mandible using lateral ramus autogenous bone graft. Patients were divided into two groups of simultaneous implant placement (group 1) and delayed implant placement (group 2). Cone-beam computed tomography (CBCT) images were obtained before augmentation, at the time of implant placement, and 10 months later (6 months after implant loading). MBL and thickness of the buccal aspect were evaluated over time. Results: There were 18 patients in the group 1 and 16 patients in the group 2. Analysis of the CBCT scans demonstrated that the mean MBL was 1.21±0.35mm in the group 1 and 1.08±0.19mm in the group 2, with no significant difference between the two groups (p= 0.19). Thickness of the buccal aspect of the augmented site at the time of implant placement was 1.85±0.20mm in the group 1 and 2.16±0.29 mm in the group 2, with a significant difference (p< 0.001). However, data analysis regarding changes in the buccal plate thickness showed no significant difference between the two groups (p= 0.36). Conclusion: According to the results of this study, there was no significant difference in M-BL and post-operative changes in the thickness of the buccal aspect of the augmented sites with onlay lateral ramus bone blocks between simultaneous and delayed implant placement.


Introduction
Alveolar ridge resorption after tooth extraction may interfere with optimal dental implant placement. The success of osteointegration depends on quality and quantity of bone in the recipient sites. Insufficient bone volume can compromise a proper implant positioning [1].
Malpositioning of dental implants can affect both the functional and esthetic outcomes [2]; thus, alveolar reconstruction is a prerequisite for implant placement [3].
A variety of surgical reconstruction options have been recommended for alveolar ridge rehabilitation.
Autogenous bone blocks are still the gold standard for Dental implant MBL following ridge augmentation with lateral ramus bone block Tabrizi R, et al 10.30476/dentjods.2022Tabrizi R, et al 10.30476/dentjods. .92419.1641 201 both vertical and horizontal augmentation because of their optimal osteoconductivity, osteoinductivity, and osteogenic potential [3][4]. Recent studies showed promising results regarding graft resorption and implant success rate following bone augmentation with intraoral autogenous bone blocks. The mandibular ramus and symphysis are the most popular intraoral sources for harvesting autogenous cortical and/or corticocancellous bone blocks [5][6][7].
Little is known about the effect of immediate and delayed implant placement in the grafted site on the long-term implant success rate and graft resorption [8].
Knowledge about the resorption rate of the graft and the final volume gain after final remodeling is imperative for treatment planning before implant placement. The primary goal of this study was to compare the marginal bone loss (MBL) and the thickness of the buccal aspect of the augmented site in simultaneous versus delayed implant placement following lateral ramus horizontal ridge augmentation in the posterior mandible.

Materials and Method
The authors designed a prospective cohort study on

Statistical analysis
The statistical analyses were performed using SPSS version 23 (SPSS Inc., IL, USA). The independent t-test was used to compare the mean age, MBL, BBT1, and BBT-changes over time between the two groups. The Chi-square test was applied to compare gender distribution. p Values <0.05 were considered statistically significant.

Results
A total of 34 patients (18 patients in the group1 and 16 patients in the group 2) participated in this study. Two patients in the group 2 were excluded as they refused to show up for the follow-up sessions. Table 1 Table 2).

Discussion
This study was designed to compare MBL and thickness of the buccal aspect of the augmented site in simultaneous versus delayed implant placement following lateral ramus horizontal ridge augmentation in the posterior mandible. Our findings suggested that the one-stage protocol (lateral augmentation with simultaneous implant placement) could be performed when adequate   In our study, the mean of MBL in one stage and two stage protocols was not different. Therefore, one-stage protocol has an advantage to two-stage protocol in reducing the treatment time and the number of surgical process. Survival and success rates of dental implants placed in horizontally resorbed edentulous ridges, which are augmented with block bone grafts, are similar to those of implants in native bone [9].
The two-stage protocol has also been suggested for some circumstances, for example, when correct threedimensional position of implant and its final restoration cannot be achieved in the first surgical appointment or when confronting a severe horizontally atrophic ridge with one-wall morphology. Several studies reported acceptable results for the staged procedure in large horizontal defects reconstructed by lateral ramus or symphysis block grafts [4,[7][8][9]. However, the most prominent benefits of the one-stage protocol such as one surgical session especially in medically compromised patients and early loading with final restoration will be lost in the two-stage protocol.
In terms of bone volume regain and MBL around dental implants in long-term, the onlay bone grafting of horizontal defects has shown less bone resorption dur-

Conclusion
According to the results of this study, there was no significant difference in MBL and post-operative changes in the thickness of the buccal aspect of the augmented sites with onlay lateral ramus bone blocks between simultaneous and delayed implant placement.